Bow thruster



p 1968 J. P. JON-ES, JR 3,400,682

BOW THRUSTER Filed Nov. 30, 1966 5 Sheets-Sheet 1 [XI-Q g INVENTOR.

Jahn P Jones Jr. F/(J. 2

BY WWW/ Af/omey Sept. 10, 1968 J. P. JONES, JR 3,400,682

BOW THRUSTER Filed Nov. 30, 1966 3 Sheets-Sheet 2 IN V EN TOR. Jo/m P James, Jr.

B FM 2/ w Afro/nay Sept. 10, 1968 J. P. JONES, JR

BOW THRUSTER 3 Sheets-Sheet 5 Filed Nov. 30, 1966 INVENTOR. John Jones, Jn BY flw/ 2/ 7% Afro/nay United States Patent 3,400,682 BOW THRUSTER John P. Jones, Jr., Scarsdale, N.Y., assignor to Mobil Oil Corporation, a corporation of New York Filed Nov. 30, 1966, Ser. No. 597,899 Claims. (Cl. 114-151) ABSTRACT OF THE DISCLOSURE This invention is directed to an improved device for maneuvering a ship. More particularly, this invention is directed to a pump driven water ejector Which exhausts into an opening extending transversely through a ship, below its water line. The ejector device induces a high mass, low velocity stream of water to pass transversely from one side of the ship to the other, thereby providing suflicient thrust to readily maneuver the vessel.

Background A persistent problem in the ship industry has been the maneuverability of ships at low or negligible speeds, at which times conventional rudder steering means are of little or no eflect. Many suggestions have been put forward for improving the maneuverability of ships under such conditions. One such system is to provide a tunnel in the bow or stern of a vessel extending athwartships. It has been suggested to place a propeller in such a tunnel to induce a flow of water through the tunnel and thus to provide a thrust perpendicular to the major axis of the ship. This type of installation is considered costly to install and maintain and the propeller is subject to damage from harbor debris.

An alternative suggestion has been to provide a pumping system which draws water directly from the sea and discharges it directly through a pipe system which provides exits on either side of the ship below the water level. A disadvantage of this system is the fact that such discharged streams are normally of high velocity which creates hazards for other boats and may damage adjacent installations such as harbor and channel facilities.

It has recently been suggested to use the present high capacity liquid transport pumps installed in tankers as bow thruster devices for improved maneuverability. These pumps do useful work only during the short time when the tanker is unloading cargo or transferring ballast. It is intended that these main cargo pumps when operating as how thrusters will pump sea water directly to one or more nozzles located along each side of the ship. However, a typical 1000-2000 horsepower turbine-driven main cargo pump will produce only 4.5-6.5 pounds thrust for each installed horsepower. This thrust does not compare well with the thrust of a typical harbor tug which delivers about 22 pounds thrust per installed horsepower. This thrust factor is caused by the high pressure and hence high nozzle exhaust velocity induced by the cargo pump which gives rise to a high kinetic energy loss per ton of thrust. In addition, the high velocity exhaust creates the problems referred to above.

It is therefore an object of this invention to provide an improved maneuvering system for ships with a high thrust factor and low exhaust velocity.

The invention FIGURE 1 depicts an embodiment of the overall thruster system of this invention.

'FIGURE 2 is a more detailed view showing the floW pattern induced by the primary nozzle.

FIGURES 3A and 3B depict two nozzle designs suita ble for use in this invention.

FIGURES 4A and 4B depict sectional views along lines IVA-IVA and IVB IVB of FIGURES 3A and 3B, respectively.

FIGURE 5 depicts a dual tunnel embodiment of this invention. FIGURE 6 depicts a two-stage ejector system for this invention.

FIGURE 7 depicts an alternative embodiment of the two-stage ejector system.

FIGURE 1 is a cross-section of a vessel 1, viewed from it bow. The port 2, starboard 3, and bottom 4 of the vessel are indicated. A tunnel 5 is shown extending athwartships through the vessel, of a generally circular cross-section. The conventional equipment aboard the vessel includes a cargo pump 6 which draws sea water through suction pipe 7 from sea chest 8 and transmits the same through discharge pipe 9. In this invention an additional discharge pipe 10 permits the sea water to be pumped through valve 11 and pipe -10 into a diverter valve 12. Additional control valves in the delivery system are indicated by 13 and 14. Valve 12 feeds either of lines 15 or 16 which respectively discharge water toward starboard and port. The discharge from 15 and 16 is directed to dual nozzle system 17 which houses the nozzles, details of the nozzles being shown in FIGURES 3A, 3B, 4A and 4B. The depicted pipes and valves have for their purpose the delivery of water to nozzle system 17. It is apparent that many other arrangements could be devise A more detailed view of the nozzle and ejector system is shown in FIGURE 2. Only the port side nozzle and mixing area are depicted, it being understood that the starboard side is similar. Water from the main cargo pump is delivered through pipe 16 into nozzle 17' and discharged as a high velocity stream indicated as V This high velocity stream induces a concurrent water flow through tunnel 5 from starboard. The velocity of this induced flow is indicated as V The high velocity stream and the induced water stream are mixed within the section of the trunnel indicated by 18. The water then passes into a diffuser section 19 which is conical as shown. The velocity of the stream at the entrance to the difluser section being indicated as V The magnitude of velocity V is intermediate between V and V The pressure variation within the tunnel produces a net force, or thrust, which acts on the vessel in a direction opposite to the direction of flow, as indicated by arrow 20.

FIGURES 3A and 3B depict two configurations for nozzle 17 as viewed from line II in FIGURE 2. A perforated plate may be positioned over nozzle 17 as indicated in FIGURE 3A and sectional view FIGURE 4A. Alternatively the nozzle may comprise a single exhaust area of the configuration indicated by FIGURE 3B and sectional view of FIGURE 4B. The exhaust areas for nozzles of FIGURES 3A and 3B are the same.

In a further embodiment of this invention a two-tunnel system may be employed, as depicted in FIGURE 5. In this embodiment one tunnel is arranged to direct water toward starboard in which case the ejector nozzle would be located nearer to the port side of the ship. The second tunnel would then direct water toward the port side of the ship with the nozzle being situated nearer to starboard. The advantage of this system is that a greater tunnel area is available for mixing and controlling the discharged streams. As depicted in FIGURE 5 the discharge pipe 10 would deliver fluid through diverter valve 12 to one of the tunnels. The tunnels themselves would be designed in a manner similar to that depicted in FIG- URE 2 (without the broken "lines on that figure). In FIG- URE 5 the nozzle 17" positioned near the' starboard side directs fluid toward port through the mixer section 18 and diffuser section 19. The other tunnel is similarly designed.

It has been shown that at lower primary stream velocities, V and higher mass flow the thrust exerted by an ejector system increases. With existing cargo pump systems an improvement in thrust can therefore be obtained by the use of more than one ejector. Various embodiments employing two or more ejectors are depicted below.

An improved embodiment of the above ejector system is the two-stage ejector depicted in FIGURE 6. In this system nozzle system 17 ejects a primary stream of water, V into a tunnel system 21, into which additional water flow, V is induced. The outlet stream, V from tunnel 21, consisting of the primary stream and induced water flow, is ejected into a main tunnel 5 and correspondingly induces a further flow, V from the water surrounding tunnel 21. Tunnel 21 is formed from a member comprising section 22 which serves as a mixing tube and section 23 which serves as a diffuser (supports therefor are not shown). Sections 18 and 19 correspond in shape and function to 22 and 23.

An alternative design for the two-stage ejector is shown in FIGURE 7. In this embodiment the shape of the main tunnel 5 is similar to that in FIGURE 5. The shape of the smaller tunnels 24 and 25 is similar to that of tunnel 21 shown in FIGURE 5. Lines 26 and 26' provide a primary stream directed to port in a manner similar to that in line 16 of the previous figures. Similarly, lines 27 and 27' serve the same function as line 15. A series of these smaller first stage ejectors may be positioned within tunnel 5.

The invention has been described in terms of specific embodiments set forth in detail, but it should be understood that these are by way of illustration only and that the invention is not necessarily limited thereto. Alternative constructions will become apparent to those skilled in the art in view of this disclosure, and accordingly modifications of the apparatus and process disclosed herein are to be contemplated within the spirit of this invention.

What is claimed is:

1. In a system for maneuvering a vessel in a body of water, the combination comprising means below the water line and extending transversely of the vessel for forming a tunnel having an at least substantially cylindrical center section, at least substantially cylindrical port and starboard mixing sections outboard of said center section, each of said port and starboard mixing sections having a cross-sectional area less than that of said center section, and outwardly diverging port and starboard diffuser sections outboard of said mixing sections to provide openings to the body of water; port and starboard nozzles in said center section, said port nozzle being directed to said port mixing section and said starboard nozzle being directed to said starboard mixing section; and means for pumping a first stream of water through one of said nozzles; whereby said one nozzle directs said first stream of water into the mixing section downstream of said one nozzle to induce a second stream of water from the body of water to flow in said tunnel means in the same direction as said first stream of water, said first and second streams of water mixing in the mixing section downstream of said one nozzle to provide through the outlet of the diffuser section downstream of said one nozzle a discharge of water having a higher mass flow rate and a lower velocity than said first stream of water.

2. In a system for maneuvering a vessel in a body of water, the combination comprising means below the water line and extending transversely of the vessel for forming a tunnel having a center section, at least substantially cylindrical port and starboard mixing sections outboard of said center section, each of said port and starboard mixing sections having a cross-sectional area less than that of said center section, and outwardly diverging port and starboard diffuser sections outboard of said mixing sections to provide openings to the body of water; port and starboard nozzles in said center section, said port nozzle being directed to said port mixing section and said starboard nozzle being directed to said starboard mixing section; and means for pumping a first stream of water through one of said nozzles; whereby said one nozzle directs said first stream of water into the mixing section downstream of said one nozzle to induce a second stream of water from the body of water to flow in said tunnel means in the same direction as said first stream of water, said first and second streams of water mixing in the mixing section downstream of said one nozzle to provide through the outlet of the diffuser section downstream of said one nozzle a discharge of water having a higher mass flow rate and a lower velocity than said first stream of water.

3. In a system for a maneuvering a vessel in a body of water, the combination comprising means below the water line and extending transversely of the vessel for forming a first tunnel having a starboard inlet end and a port outlet end, means below the water line and extending transversely of the vessel for forming a second tunnel having a port inlet end and a starboard outlet end, means for pumping water to one of said first and second tunnel means, first nozzle means located in the vicinity of the inlet end of said first tunnel means for directing the water from the pumping means toward the outlet end of said first tunnel means, and second nozzle means located in the vicinity of the inlet end of said second tunnel means for directing the water from said pumping means toward the outlet end of said second tunnel means, whereby the nozzle means in said one tunnel means produces a first stream of Water in said one tunnel means, said first stream of water including a second stream of water to flow in said one tunnel means from the body of water through the inlet end of said one tunnel means, said first stream of water inducing a second in said one tunnel means to provide through the outlet end of said one tunnel means a discharge of water having a higher mass flow rate and a lower velocity than said first stream of water.

4. The system of claim 3 wherein each of said first and second tunnel means comprises a mixing section into which said first stream of water is directed and an outwardly diverging diffuser section interconnecting the outlet end and the mixing section.

5. The system of claim 3 wherein each of said first and second tunnel means comprises an at least substantially cylindrical mixing section into which said first stream of water is adapted to be directed, and an outwardly diverging diffuser section interconnecting the outlet end and the mixing section.

References Cited FOREIGN PATENTS 5/1935 Germany. 6/1966 Great Britain.

U.S. DEPARTMENT OF COMMERCE PATENT OFFICE Washington, 0.0. 20231 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTIDN Patent No. 3,400,682 September 10, 1968 John P. Jones, Jr.

It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

Column 4, line 42, "including" should read inducing line 45, "said first stream of water inducing a second" should read and said first and second streams of water mixing Signed and sealed this 10th day of February 1970.

(SEAL) Attest:

Edward M. Fletcher, Jr.

Attesting Officer Commissioner of Patents 

